Summary: Reasons for performing study: Sepsis is an important cause of death in foals. Knowledge of which pathogens are likely to be involved is important for selection of antimicrobial drugs for initial treatment. Objectives: To identify temporal trends in prevalence of bacteria isolated from foals with sepsis between 1979 and 2010. Study design: Retrospective review of medical records. Methods: All foals ≤30 days of age presented to the V eterinary M edical T eaching H ospital ( VMTH) at the University of California, D avis between 1979 and 2010, with a diagnosis of sepsis confirmed by culture of bacteria from blood or internal organs ( antemortem or at necropsy), were included in the study. Conventional microbiological methods were used to identify isolated organisms. The C ochran– A rmitage trend test was used for statistical analysis. Results: The percentage of G ram‐positive isolates increased significantly over the years. The percentage E nterobacteriacea , and K lebsiella spp. in particular , decreased over time. E nterococcus spp. isolates were cultured more often in recent years. Conclusions: Whereas G ram‐negative bacteria, particularly E nterobacteriaceae, remain the most common isolates from neonatal foals with sepsis, the prevalence of G ram‐positive bacteria is increasing. This trend underlines the importance of including antimicrobial drugs active against both G ram‐positive and G ram‐negative bacteria in treatment protocols while awaiting the results of bacteriological culture and susceptibility tests. The increased prevalence of E nterococcus spp. is of concern because antimicrobial susceptibility patterns for enterococci are unpredictable and enterococci can also act as donors of antimicrobial resistance genes to other bacteria.

Summary: Reasons for performing the study: Monitoring the development of antimicrobial resistance is important for the rational selection of appropriate antimicrobial drugs to initiate treatment of foals with sepsis. Objectives: To identify temporal trends in antimicrobial susceptibility patterns of bacteria isolated from foals with sepsis. Study design: Retrospective review of medical records. Methods: Foals aged <30 days with a diagnosis of sepsis, confirmed by culture of bacteria, were included. Susceptibility data, expressed as minimum inhibitory concentrations (MICs) (MIC ₅₀ , MIC ₉₀ , MIC range) and percent of isolates that were susceptible to a particular antimicrobial drug, were compared for bacteria isolated from foals during 3 different time periods: 1979–1990, 1991–1997 and 1998–2010. The C ochran‐ A rmitage trend test and the J onckheere‐ T erpstra test were used for statistical analysis. Results: A total of 1091 bacterial isolates were cultured from 588 foals. E nterobacteriaceae, A ctinobacillus spp . and β‐haemolytic S treptococcus spp . showed a decrease in percent of isolates susceptible to gentamicin over time. E nterobacteriaceae, A ctinobacillus spp . and β‐haemolytic S treptococcus spp. showed an increase in MIC values for amikacin. E nterobacteriaceae showed a decrease in percent of isolates susceptible to ceftiofur. E nterococcus spp . and P seudomonas spp. showed increased MIC values to ceftiofur. E nterobacteriaceae showed increased MIC values to ceftizoxime. E nterococcus spp . became more resistant to imipenem and showed increased MIC values to ticarcillin/clavulanic acid. In contrast, several trends in increased susceptibility were also seen. Conclusions: Based on these in vitro results, the combination of amikacin and ampicillin remains an appropriate choice for initiating treatment of sepsis in foals while awaiting culture and susceptibility test results, although increasing development of resistance to amikacin was demonstrated. The decrease in in vitro activity of ceftiofur against E nterobacteriaceae is of concern. Similarly, the development of resistance of E nterococcus spp. to imipenem is an important finding that warrants monitoring in the future. Judicious use of antimicrobials is therefore crucial.

Several studies have described the faecal microbiota of horses and the factors that influence its composition, but the variation in results is substantial. This study aimed to investigate the microbiota composition in healthy equids in The Netherlands under standard housing and management conditions and to evaluate the effect of age, gender, horse type, diet, pasture access, the season of sampling and location on it. Spontaneously produced faecal samples were collected from the stall floor of 79 healthy horses and ponies at two farms. The validity of this sampling technique was evaluated in a small pilot study including five ponies showing that the microbiota composition of faecal samples collected up to 6 h after spontaneous defaecation was similar to that of the samples collected rectally. After DNA extraction, Illumina Miseq 16S rRNA sequencing was performed to determine microbiota composition. The effect of host and environmental factors on microbiota composition were determined using several techniques (NMDS, PERMANOVA, DESeq2). Bacteroidetes was the largest phylum found in the faecal microbiota (50.1%), followed by Firmicutes (28.4%). Alpha-diversity and richness decreased significantly with increasing age. Location, age, season, horse type and pasture access had a significant effect on beta-diversity. The current study provides important baseline information on variation in faecal microbiota in healthy horses and ponies under standard housing and management conditions. These results indicate that faecal microbiota composition is affected by several horse-related and environment-related factors, and these factors should be considered in future studies of the equine faecal microbiota.

Diagnosing IBD in horses is challenging and requires a multimodal approach, since no conclusive diagnostic test is available. The objectives of this study were to provide an overview of population characteristics, results of applied diagnostic tests, treatment modalities and outcome in a large group of horses thought to have IBD and that were presented to four large equine referral hospitals, and to provide an exploratory investigation of possible associations between results of applied diagnostic tests, applied treatment modalities and outcome. A retrospective case series was performed across four large equine referral hospitals. Seventy-eight horses, thought to have IBD were included. Case history, clinical findings, diagnostic test results including oral glucose tolerance test (OGTT) and enteral biopsies (both duodenal and rectal), applied therapy and outcome were studied. A Chi-Square test was used to identify associations between results of diagnostic tests, treatment and outcome. P-values < 0.05 were considered significant. Lethargy, diarrhoea, recurrent colic and weight loss were recorded in respectively 21,8%; 14,1%; 28,2% and 78,2% of cases. Over 70% of horses thought to have IBD had an abnormal OGTT. Only weight loss was significantly associated with aberrant enteral biopsy results, but not with abnormal OGTT results or low blood total protein. There was no association between an aberrant biopsy result and a disturbed OGTT. There was no association between either OGTT results or enteral biopsy results and a low blood total protein content, presence of gastric ulcer disease or an aberrant endoscopic aspect of the duodenal entrance. Weight loss is a highly prevalent symptom in IBD suspected horses. Enteral biopsies may be a useful diagnostic aid in the work-up of horses thought to suffer from IBD, however further research is required to demonstrate their true diagnostic value. Until more standardized scientific research is available, one should be careful with the interpretation of enteral biopsy results There is a need for better standardization of enteral biopsy procedures and the histopathological scoring of biopsies.